sim/ppc/README.psim

   1
   2                         PSIM
   3
   4 Copyright (C) 1994-1995, Andrew Cagney <cagney@highland.com.au>
   5
   6 This directory contains the program PSIM that models the PowerPC
   7 architecture.  It can either be run stand alone (psim) or linked with
   8 GDB.
   9
  10
  11 CONTENTS:
  12
  13     psim-*.tar:
  14
  15         psim-sim-*.tar.gz       simulator source code
  16
  17         psim-test-*.tar.gz      test directory for simulator
  18
  19         psim-gdb-*.diff.gz      patches to integrated psim
  20                                 into gdb
  21
  22     gnu-*.tar:
  23
  24         gnu-gdb-*.diff.gz       patches to gdb that may have
  25                                 already been merged into the
  26                                 GDB source tree.
  27
  28         gnu-*-*.diff.gz         Other noise
  29
  30
  31 BUILDING:
  32
  33         o Install flex, bison, gnu-make, native gcc and probably also byacc.
  34
  35
  36         o First you will need a fairly current copy of GDB (try the ftp site
  37           ftp.cygnus.com:pub).  I've built it with a beta version of gdb-4.15.
  38
  39           Unpack gdb vis:
  40
  41                 $ gunzip < gdb-4.15.tar.gz | tar xf -
  42
  43
  44         o Apply any patches that haven't yet been merged into the GDB source
  45           tree.
  46
  47                 $ cd gdb-4.15
  48                 $ gunzip < ../psim-gdb-*.diff.gz | patch -p1
  49                 $ gunzip < ../gnu-gdb-*.diff.gz | patch -p1
  50
  51
  52         o Unpack the psim source code (and optionally the test directory)
  53
  54                 $ cd gdb-4.15
  55                 $ gunzip < ../psim-sim-*.tar.gz | tar xvf -
  56                 $ gunzip < ../psim-test-*.tar.gz | tar xvf -
  57
  58
  59         o Configure gdb as per normal.  I use something along the lines of:
  60
  61                 $ cd gdb-4.15
  62                 $ CC=gcc ./configure --target=powerpcle-unknown-eabi
  63
  64
  65         o Build your entire gdb tree as per normal.  Something along the
  66           lines of:
  67
  68                 $ cd gdb-4.15
  69                 $ make CC=gcc
  70                 .
  71                 .
  72                 .
  73
  74
  75
  76         o Install it it all as per normal.  Something along the lines of:
  77
  78                 $ cd gdb-4.15
  79                 $ make CC=gcc install
  80
  81           The program sim/ppc/psim is not installed.
  82
  83
  84 RUNNING:
  85
  86         PSIM can either be run as a stand alone program or as part
  87         of gdb.  The psim-test archive contains pre-compiled and
  88         linked programs that can be run on PSIM.  The notes below
  89         assume that you have unpacked that tar archive.
  90
  91         To rebuild the archive you will need to obtain a working
  92         version of an ELF compiler/linker for the PowerPC.
  93
  94         Example of running PSIM:
  95
  96                 Print out the users environment:
  97
  98                         $ sim/ppc/psim sim/ppc/test/envp
  99
 100                 Print out the arguments:
 101
 102                         $ sim/ppc/psim sim/ppc/test/argv a b c
 103
 104                 Check the OEA model:
 105
 106                         $ sim/ppc/psim sim/ppc/test/interrupt
 107
 108                 Check that sbrk works
 109
 110                         $ sim/ppc/psim sim/ppc/test/break
 111
 112                 Try for speed.  The program count contains a loop
 113                 of two instructions which is looped <arg> times.
 114                 See later for how to make PSIM run 10-100 times
 115                 faster.
 116
 117                         $ time sim/ppc/sim sim/ppc/test/count 5000000
 118                         $ expr 10 \* 1000 \* 1000 / <seconds>
 119
 120
 121         Example of running GDB:
 122
 123                 The most important thing to be aware of is the fact
 124                 that before the simulator is used, the user must attach
 125                 to it (target sim) and than load the executable (load count).
 126
 127                         $ cd sim/ppc/test
 128                         $ powerpc-unknown-eabi-gdb count
 129                         (gdb) target sim
 130                         (gdb) load count
 131                         (gdb) break main
 132                         (gdb) run
 133                         .
 134                         .
 135                         .
 136
 137
 138 CONFIGURATION: Making it go faster
 139
 140         See the file sim/ppc/config.h (a.k.a. sim/ppc/data/ppc-config)
 141         for notes.
 142
 143
 144 KNOWN FEATURES
 145
 146         SMP, dual-endian, VEA and OEA models, hardware devices
 147         (console, icu, reset) ...
 148
 149
 150 KNOWN PROBLEMS:
 151
 152         Configuration could be better.
 153
 154         HTAB (page) code for OEA model untested.  Some of the vm code
 155         instructions unimplemented.
 156
 157         Doesn't detect/handle changing endian bits.  In fact they are
 158         ignored.
 159
 160         Return from interrupt instruction unimplemented.
 161
 162         Flush instruction cache instructions do nothing.  Perhaphs they
 163         should (if there is an instruction cache) flush it.
 164
 165         PowerOpen VEA model (a.k.a XCOFF a.k.a AIX) broken.  It was
 166         working but that is before I changed the create stack frame
 167         code into an ELF version.
 168
 169         OpenBoot and PR*P interfaces missing.  Open boot could be
 170         implemented by putting special instructions at the address
 171         of the OpenBoot callback functions.  Those instructions
 172         could than emulate OpenBoot behavour.
 173
 174         VEA memory read/write performance could be improved by merging
 175         the data sections.
 176
 177         When reading in a VEA executable, the binaries text and data
 178         sections are not made page aligned.
 179
 180         Missing or commented out instructions.
 181
 182         Lack of floating point support.
 183         [workaround: build everything using -msoft-float]
 184
 185         64bit untested.
 186
 187         Event code for pending events from signal handlers not
 188         finished/tested.
 189
 190         Better and more devices.
 191
 192         Only two device trees VEA and OEA (clayton) and those hard coded.
 193         Should be possible to specify a file containing a device tree
 194         description as the program to run.  At present it a device tree
 195         file is detected causing psim to abort.
 196
 197         I wonder if I've got my ppc.instructions copyright
 198         notice correct.
 199
 200
 201 THANKS:
 202
 203         Thanks go to the following who each helped in some way.
 204
 205                 Allen Briggs, Bett Koch, David Edelsohn,
 206                 Michael Meissner, Bob Mercier, Richard Perini,
 207                 Richard Stallman, Mitchele Walker
 208
 209
 210 ----------------------------------------------------------------
 211
 212
 213 Random notes on performance:
 214
 215
 216 $ cd test
 217 time ../psim count `expr 10000000 / 2`
 218 time ../psim volatile-count `expr 10000000 / 7`
 219
 220 Where 2 and 7 are the number of instructions in the main loop.
 221
 222
 223         611/729 - baseline
 224
 225 Tests:
 226
 227         CFLAGS= -c -O2 -m486 -fomit-frame-pointer
 228
 229         o       different first/second level table/switch combinations
 230
 231                 0 - use a table
 232                 1 - use a simple switch
 233                 2 - use an expanded switch
 234
 235 i486DX4/100 - AMD
 236
 237         1/108/140 - switch=0/0/0,expand=2,inline=2,nia=1,cache=1
 238         1/114/140 - switch=0/0/0,expand=2,inline=2,nia=1,cache=1
 239         1/137/149 - switch=0/0,expand=2,inline=1,nia=1,cache=1
 240         1/144/155 - switch=2/1,expand=2,inline=1,nia=1,cache=1
 241         1/153/159 - switch=2/1,expand=0,inline=1,nia=1,cache=1
 242         1/185/189 - switch=0/0,expand=0,inline=1,nia=1
 243
 244 i486DX2/66
 245
 246         1/572/695 - switch=1/1,expand=0,inline=0
 247         1/579/729 - switch=0/0,expand=0,inline=0
 248         1/570/682 - switch=2/2,expand=0,inline=0
 249         1/431/492 - switch=0/0,expand=0,inline=1,nia=0
 250         1/271/292 - switch=2/1,expand=0,inline=1,nia=0
 251         1/270/316 - switch=2/2,expand=0,inline=1,nia=0
 252         1/271/281 - switch=1/1,expand=0,inline=1,nia=1
 253         1/267/274 - switch=2/1,expand=0,inline=1,nia=1